How to outline your bms requirements

Answering a number of questions will allow the determination of what the BMS is required to handle. Since the BMS is there to integrate between several systems these need to be outlined within you application to make sure you have the correct components to provide the necessary protection and operating functionality.

Here is how you can outline your hardware requirements.

What type of cell are you planning to use to make a battery pack?

Outline the following
  • Manufacturer and Model 
  • Packaging format ( 18650, 26650, Pouch, Prismatic, other)
  • Chemistry and nominal voltage
  • Cell Capacity (typically in Ah)
  • If known, operating voltage range min / max
  • If known, operating temperature range min / max
  • New / Recycled cells
  • If recycled
    • what was their original application (i.e. Vehicle,laptop, etc..)
    • age, shelf life when fabricate
    • kilometers travels to indicate the accumulated kWh charge/discharge thus far.

How do you plan to configure the cells into a pack

  • Number of cell strings
  • Number of cells in series
  • Number of cells in parallel
  • Proposed cell monitors if known to this configuration
  • Do you have individual cell fusing
  • What is the cell string fusing rating.
  • With several strings what is each string protection rating

What are you connected the battery to Charger / Inverter

  • Manufacture / model of charger
  • Manufacture / model of load/discharge Inverter
  • Is the charger / Inverter integrated into one(1) unit or separate components
  • Does the charger have a communication port? If so do you have the communication protocol that is used? 
  • Does the load/discharge equipment (i.e. inverter)  have a communication port? If so do you have the communication protocol that is used? 
  • peak charging / discharge currents
  • continuous charging / discharge currents
  • peak voltage that will be measured from the battery pack
  • what is the minimum voltage required to run the inverter/charger
  • will this be directly links to a vehicle alternator (or dynamo) ?

Do you want to know the SoC%

State of Charge (aka. Fuel Gauge) helps determine the operating condition and requires additional shunt hardware.
  • peak charging / discharge current
  • continuous charging / discharge current
  • peak voltage that will be measured from the battery pack
  • Where in the circuit will the shunt be installed (typically near the negative terminal)

What protection is required

  • Will you be using a Circuit breaker?
  • If using a Circuit breaker to the battery will this have a remote trip function
  • What is the rated current for the circuit breaker (dual pole positive/negative)
  • Are there contactors / relays to protect the battery if required
  • monentary / or latching 
  • accessory coil voltage  5v/12v/24v/48v or other
  • Is there a need for the precharge circuit?
  • Are there any permanent accessory circuits connected to the battery that continue to supply power ever when the critical circuit breakers have been disengaged.

What environment will the cell be used

  • Stationary (fixed) or mobile (vehicle)
  • If mobile what is the accessory voltage (i.e. 12v)?

Connectivity

Will this be linked to the network to have internet access via wifi?

Related References

Why do I need a starter kit not just the CellMons or WatchMon

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